1. Field of the Invention
Embodiments of the present invention relate, in general to home healthcare monitoring and more particularly to monitoring and correlating trend data with respect to ankle displacement measurements and patient weight and thereafter transmitting that data to a healthcare professional when a statistically significant event occurs.
2. Relevant Background
Congestive heart failure, or heart failure, is a condition in which the heart cannot pump enough blood to the body's other organs. This can result from a variety of causes including narrowed arteries that supply blood to the heart muscle, coronary artery disease, scar tissue build up from past heart attack or myocardial infarction that interferes with the heart muscle's normal work, high blood pressure, heart valve disease due to past rheumatic fever or other causes, heart defects present at birth, and infection of the heart valves and/or heart muscle itself.
Congestive heart failure is a condition in which the heart, while continuing to function, does not perform its work as efficiently as it should. People with heart failure cannot exert themselves because they become short of breath and fatigued. As blood flow out of the heart slows, blood returning to the heart through the veins backs up, causing congestion in the tissues. Often swelling (edema) results. Most often there is swelling in the legs and ankles, but swelling can occur in other parts of the body as well. Sometimes fluid collects in the lungs and interferes with breathing, causing shortness of breath, especially when a person is lying down. Another common symptom is swelling in lower extremities, especially the feet and ankles.
The degree of swelling people with heart failure experience depends on how well their body is compensating for the heart failure and how much sodium and water their body retains. In some cases the swelling is mild and merely bothersome, while in other cases it can be severe and painful as their skin becomes taut and sensitive.
The medical term for this swelling in the legs is pedal edema—“pedal” refers to the feet and “edema” refers to the buildup of excess fluid. Heart failure often causes what doctors call “pitting edema,” meaning that applying pressure to the swollen skin leaves an indentation in the skin. Doctors often test for edema by pressing their thumb to the skin and seeing whether it leaves an impression. One common example of pitting edema is when, upon removal of one's footwear, he or she discovers that his or her socks have left an impression in the skin of the ankles and feet. However, tests such as this are used to confirm extreme cases of edema after a patient has sought assistance. The presence of edema is used to verify or support a diagnosis rather than proactively to identify a potential or growing condition.
While the association of pedal edema and heart failure is well known, the presence of pedal edema in a patient experiencing heart failure is typically one of many factors used to reach a diagnosis once a patient has sought out medical care. For example a chest X-ray indicating a build up of fluid in the cavity surrounding the lungs resulting in the patient experiencing difficulty in breathing may also be indicative of heart failure. But unlike blood tests, X-rays and other non-ambulatory tests, pedal edema can be readily observed and monitored by the patient.
However, even when patients having a high likelihood or susceptibility to heart failure are asked to monitor various physiological conditions including pedal edema, patient compliance is historically poor and unreliable. A need therefore exists for a system and apparatus to efficiently and effortlessly monitor changes in pedal edema of a patient showing susceptibility to heart failure. Furthermore there is a need to record such data and correlate it with the weight of a patient over a period of time so as to determine whether any changes in pedal edema are consistent or inconsistent with weight change. Finally a need remains to convey this information to a healthcare professional for analysis and, if necessary, to initiate proactive measures to minimize risk to the patient. These and other improvements to the prior art are hereafter described by way of example.